Do You Know about the Metal Oxide Varistor?

What is the MOV Varistor?

The MOV varistors are referred to VSR, meaning "resistance values in a certain range of current and voltage with the voltage change", or the resistance value of the voltage sensitive resistor, a voltage-sensitive nonlinear overvoltage protection of the semiconductor element. In the circuit, it uses text symbol "RV" or "R". The resistor body of the varistor material is a semiconductor, so it is a species of the semiconductor resistor. Now the extensive use of the zinc oxide (ZnO) varistor, divalent element (Zn) and hexavalent element oxygen (O) constituting its body material. Therefore, from the point of view of the material, the zinc oxide chip varistor is a "the 2 - VI family oxide semiconductor.

Types of the Varistor
mov metal oxide varistor can be divided according to its classification structure, the manufacturing process and the use of materials and the volt-ampere characteristics. First, according to structure, it can be divided into structural classification varistors, junction body varistors, single the particles layer of pressure-sensitive resistor and film pressure sensitive resistor. Junction type varistor is because of a special contact between the resistive element and the metal electrode, before having the nonlinear characteristics, body varistor nonlinearity is determined by the semiconducting properties of the resistor element itself. Second, according to varistor material classification, and by the use of their materials can be divided into zinc oxide varistors, silicon carbide varistors, metal oxide varistors, germanium (silicon) varistors titanate barium varistors and other kinds. Third, according to the voltage characteristics,they are classified into symmetric varistors (polarity) and asymmetric varistors (polarity).

Selection Principle of the MOV Varistors
If the voltage level of electrical equipment Vo is low, and the surge of energy and relatively is large, you can choose the varistor voltage V1mA lower and the larger diameter varistors; if Vo is higher, you can select the varistor voltage of V1mA of higher varistors, so it not only can protect the electrical equipment, but also to extend the useful life of the varistor. Varistors are used in a variety of electronic products, and over-voltage protection circuit. It has a variety of models and specifications. The main parameters of the selected varistor (including nominal voltage, maximum continuous operating voltage, the maximum limit voltage, flow capacity, etc.) must comply with the requirements of the application circuit, in particular, it is the nominal voltage. If the nominal voltage is too high, it will not achieve overvoltage protection, if nominal voltage is too low, the varistors are easy to malfunction or breakdown.

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